Strictly speaking, cloning is the creation of a genetic copy of a sequence of DNA or of the entire genome of an organism. In the latter sense, cloning occurs naturally in the birth of identical twins and other multiples.
The secondary nutrients, calcium (Ca), magnesium (Mg) and sulfur (S), are as important to plant nutrition as the primary nutrients. Deficiency in secondary nutrients, including Ca, can depress plant growth as much as primary nutrient deficiencies do.he secondary nutrients, calcium (Ca), magnesium (Mg) and sulfur (S), are as important to plant nutrition as the primary nutrients. Deficiency in secondary nutrients, including Ca, can depress plant growth as much as primary nutrient deficiencies do.
Although there is sufficient iron in most soils for plant growth, plant iron deficiency is a problem in calcareous soil, due to the low solubility of iron(III) hydroxide. Calcareous soil accounts for 30% of the world's farmland.